1. Field of the Invention
The field of the invention relates to mixing bowls wherein a combination of liquid and powdered materials are mixed, and, more specifically, to disposable, handheld dental mixing bowls.
2. Description of the Prior Art
In the practice of dentistry, dentists must oftentimes mix various materials, such as is required in the formation of artificial stone, plaster, alignate and water, and also in the mixing of certain dental repair material of the two-part type in which a plastic ingredient and a catalyst are employed.
The weights and forces and quantities of such materials involved in a single mixing necessary to achieve a uniformity of mixing of all of the materials and liquids involved, all previously required the use of permanent, relatively staunch and durable reuseable containers. The use of such containers involves considerable initial expense, and requires repeated, time-consuming maintenance, such as cleaning, and sterilizing.
The prior art consists largely of the use of mixing bowls, spoons and spatulas to mix liquid and powdered materials into a paste used for creating impressions of a patient's teeth commonly referred to as dental impressions.
Dentists use alignate which is a salt of alginic acid, such as sodium alginate or magnesium alginate, to prepare castings of their patients' teeth. Alginates possess properties which make them suitable for surgical dressings, dental impression material, and the like. Initially, the alginate is in a dry powder form. To prepare the alginate for such dental applications, the dentist will place a certain amount of the alginate into a bowl and add water. The amount of alginate powder and water required will vary depending upon the brand of alginate used. This precise amount to be mixed with a certain amount of water is information which is generally provided by the manufacturer.
"Alginate" is the term used herein to refer to an irreversible alginate-based hydrocolloid. Several sources of alginate are found commercially which are useful for this purpose. Such sources of alginate are comprised of approximately 12 to 15% sodium alginate which is used as a reactant, approximately 8 to 12% calcium sulfate dihydrate, which is used as a reactant, approximately 2% sodium phosphate or sodium carbonate which is used as a retarder, and approximately 70% reinforcing filler such as diatomaceous earth. Alginate is available commercially under various brand names such as Algiden.RTM., Co-Alginate.RTM., Hydro-Jel.RTM., Jeltrate.RTM., and Supergel.RTM., among others.
The alginate and water mixture must have a pasty gel-like flowable consistency. It cannot be too soupy, nor too dry, and powdery `pockets` in the mix are unsatisfactory. Thus, the water must be added in exact proportions and then mixed thoroughly to ensure that the water is evenly distributed. This generally entails mixing the alginate in a bowl either with a spatula or by machine. The spatula method is messy and the machine method requires the purchase of a machine. Both methods require clean-up after the mixing is finished. In addition, the spatula method also requires a certain level of skill. The alginate and water must be mixed vigorously to ensure thorough distribution of the water to all the powder in the mixing bowl. However. the mixing must be gentle until the mixture becomes substantially pasty in order to avoid loss of the powder.
After the mixture is formed, the dentist will place in it a mouth-sized preformed impression tray that will then be placed in the patient's mouth to form an imprint of his or her teeth. When the alginate hardens, it can be used to form a casting of the patients' teeth by pouring an alpha modified gypsum or plaster-of-Paris or another similar substance into the imprint.
The traditional dental mixing bowl is formed of rubber and has relatively thick sidewalls and is made to be used over and over again. After mixing the combination of liquid and finely powdered material in the dental mixing bowl, the rubber mixing bowl must be cleaned. Cleaning this rubber bowl is a time consuming job and usually the unused mixed material is flushed down the sink. Oftentimes, the plumbing drain system gets clogged with the mixed dental material requiring a plumber to unclog the drain.
Additionally, the reuse of the rubber bowl creates the continuing risk of the transmittal of infectious diseases due to the lack of being able to fully and completely sanitize the inside surface of the rubber bowl where the mixing of the liquid and the powdered materials takes place.
It is not unusual for a dentist to use the very same rubber dental mixing bowl throughout the dentist's entire working lifetime.
In the past, such may have been an acceptable practice and use of a rubber dental mixing bowl during an era of smaller populations coupled with, regional isolation between various populations over long periods of time, fewer diseases, fewer exotic diseases, such as Hepatitis A, B, and C, Mad-Cow Disease, various strains of virally-caused flus, blood and body fluids transmitted diseases, such as AIDS, tuberculosis, along with fewer encounters with large groups of people. There is no known and acceptable, non-destructive method for sanitizing the traditional rubber dental mixing bowl.
Further, the traditional rubber dental mixing bowl is made to be re-usable and is not considered disposable.
Additionally, the traditional rubber dental mixing bowl has a wall which is formed to be relatively and uniformly thick, with the thickness of the wall defining the degree of manual flexibility of the wall of the bowl during the manual mixing process between the liquid and the powdered materials. The wall of the mixing bowl must be relatively stiff over about a two (2) inch span of wall, and, yet allow for manual manipulation of the wall of the mixing bowl to promote the mixing process as the bowl is rotated by one hand while the other hand is using a spoon-like mixing device.
Examples of the prior art include the following prior art patents:
U.S. Pat. No. D-59,956 relates to a design patent for an individual ice cream container. While this container has the vertically-disposed ribs on the wall about the outside of the body of the bowl, all of the ribs are contiguous rather than spaced-apart as in the inventive product described herein. The ribs are spaced apart to allow the fingers of the user to manipulate the bowl and to rotate it to enhance the mixing process. Additionally, the base or bottom of the bowl is shaped in the form of several hemispherically-shaped knobs instead of the hollow base with a continuous rim thereabout formed as an integral part of the bottom of the bowl and taught by the instant invention disclosed herein.
U.S. Pat. No. D-112,949 relates to the design of a cup. This particular cup design has external, vertically-arranged ribs which are spaced apart, the ribs extend from the bottom of the bowl to the rim of the cup. The ribs in the within described product do not extend from the bottom to the top of the rim as does the cup shown in this patent. Another distinctive difference between the presently disclosed product and the within invention is that the base of the presently disclosed product is within the diameter of the bottom of the bowl.
U.S. Pat. No. D-151,431 relates to the design of a cup having elongated ribbed portions thereon.
U.S. Pat. No. D-190, 878 discloses the design of a shallow pitcher with a laterally extending lipped portion about the rim of the pitcher.
U.S. Pat. No. D-199,319 relates to the design of a drinking tumbler having a plurality of elongated ribbed portions thereabout.
U.S. Pat. No. D-203,340 relates to a design for a "mixing apparatus for dental materials".
U.S. Pat. No. D-237,770 relates to a design for a pitcher which looks very similar to a flower pot.
U.S. Pat. No. D-258,085 discloses a design for an electric dental material mixer. It appears that the traditional rubber mixing cup or bowl is positioned on top of the housing for the electric mixing apparatus.
U.S. Pat. No. D-259,011 teaches a design for a mixing bowl or the like. In addition to the base, this design shows a outwardly extending rimmed portion with a section to be utilized for pouring liquid from the mixing bowl.
U.S. Pat. No. D-287,917 is a design patent for a microwave oven covered dish.
U.S. Pat. No. D-313,148 relates to a design patent covering a bowl with a tabbed portion extending from the rim of bowl for manually gripping the rim of the bowl to hold the bowl during mixing activities.
U.S. Pat. No. D-373, 932 covers a mixing bowl design.
U.S. Pat. No. 3,407,924 relates to a method and package for producing dental molds or molding material. A package unit of a container containing compressed gypsum powder material compressed and sealed is disclosed in this patent along with the method of producing a liquid-gypsum mixture used in dental application. The package serves as the mixing container for the dental model material. The container is disposable.
U.S. Pat. No. 3,610,586 teaches a mixing device for dental products that uses a disposable cup made of plastic.
U.S. Pat. No. 3,659,825 relates to a dish for mixing denture repair materials. An internally-ribbed, relatively thin walled container 12 is used as part of a two part container system as shown and illustrated in FIG. 1. The dish for mixing dental repair material is made from plastic and is intended to be disposed of when the mixing is finished.
U.S. Pat. No. 5,709,467 teaches a device for mixing alginate and may be discarded after use.
The problems associated with the prior art have been solved by creating a disposable dental mixing bowl with a thin wall made of plastic material, along with external ribs to enhance and add structural support and a measured degree of stiffness to the sidewall of the bowl. The plurality of vertically-arranged, externally disposed ribs additionally provide a series of longitudinally arranged, raised portions extending from the base of the bowl to a point adjacent to the rim of the bowl to allow the bowl to be manually rotated while the materials are being mixed. This greatly improves the speed at which such combination of liquid and powdered material can be mixed, combined and rendered uniform. Since the dental mixing bowl is disposable, it is used only once and the bowl, along with the remaining material in the bowl, is simply disposed of by tossing the entire combination, bowl and all, into the trash can. This eliminates the need to wash the materials out of the dental mixing bowl and into the plumbing drain which frequently produces stoppage of the plumbing drain. In summary, not only does the new and unique disposable thin wall plastic mixing bowl eliminate the risk of the transmittal of infectious diseases such as in the case when the prior art rubber mixing bowl is used, but the use of the new bowl also eliminates the usual plumbing blockage problem as well because the bowl is simply tossed into the trash and the remaining mixed materials are not flushed down the plumbing drain as is the procedure when using the prior art rubber, non-disposable dental mixing bowl.